Study On The Surface Modification Of Ramie Fiber And The Fiber Reinforced Polymer Composites For Automobile

In order to alleviate the pressure on the environment and resource, it is more and more interesting that the recyclable and environmentally friendly materials are used in automotive industry. This paper prepared the environmentally friendly, eco-performance composite materials with reusable thermoplastic polypropylene alloy (PP) as matrix and biodegradable natural ramie fiber (RF) as reinforcement.The surface hydroxyl value of ramie fiber was determined by a new method as isocyanate group backtitration (IBT) firstly, and then the ramie fiber was treated with epoxy-silicone oil (ESO). Finally, the modified RF/PP composites were prepared by a hybrid molding technology of extrusion and injection. It was investigated by FTIR, XRD, SEM, TG, contact angle measurement and mechanical properties’tests that how the treatment played effect on the surface properties and the microstructure of modified ramie fiber, and the interface compatibility, the mechanical properties and the heat resistant of modified RF/PP composites.The results show that the surface hydroxyl value of ramie fiber is150mgKOHIg, indicating that there is a very few number of hydroxyl groups on the surface of ramie fiber. Furthermore, the ESO chains were grafted onto the surface of ramie fiber after3hours reaction in the autoclave at160℃in argon gas. XRD patterns showed it was changed lower that the crystallinity of modified ramie fiber. Contact angle test confirmed that the polarity of modified ramie fiber was reduced significantly, resulting in improving the interfacial compatibility of modified ramie fiber and polypropylene alloy, and improving the properties of RF/PP composites. The impact strength of RF/PP composites was increased significantly after ESO treatment, while the tensile strength and the bending strength of the composites were increased little. The impact strength was increased by17.0%with the fiber content of30wt%after the fiber treatment. Moreover, with the fiber content in composite increasing, the tensile strength and the flexural strength of RF/PP composites were increased, while the impact strength was reduced. When the fiber content was30wt%, the tensile strength and the bending strength of modified RF/PP composites were increased by37.0%and69.5%respectively, compared to pure PP. In addition, TG analysis showed that the heat resistance of modified RF/PP composites was also improved.The prepared composite in this paper is probably applied in automotive field as a new interior material and the research findings could promote the development of automotive industry.